This invention relates generally to semiconductor manufacture, and specifically to a method for fabricating semiconductor components and interconnects with contacts on opposing sides.
Semiconductor components include external contacts that allow electrical connections to be made from the outside to the integrated circuits contained on the components. A semiconductor die, for example, includes patterns of bond pads formed on the face of the die. Semiconductor packages, such as chip scale packages, also include external contacts. One type of semiconductor package includes solder balls arranged in a dense array, such as a ball grid array (BGA), or fine ball grid array (FBGA).
Typically, a component includes only one set of external contacts on either the face side (circuit side) or the back side of the component. However, it is sometimes necessary for a component to have external contacts on both sides. For example, for stacking a semiconductor package to another identical package, external contacts can be formed on the face of the package and on the back side as well. U.S. Pat. No. 6,271,056 to Farnworth et al. discloses this type of stackable package.
Interconnects configured to make electrical connections with semiconductor components also include external contacts. A wafer probe card is one type of interconnect adapted to make electrical connections between external contacts on a wafer under test, and test circuitry associated with a wafer handler. Another type of interconnect is adapted to electrically engage unpackaged dice, or chip scale packages, packaged within a test carrier. U.S. Pat. No. 5,541,525 to Wood et al. discloses this type of interconnect and test carrier.
In each of these examples, the interconnect includes external contacts for electrically engaging the external contacts on the semiconductor component. With a conventional needle probe card the external contacts comprise probe needles. With an interconnect used with a test carrier as described above, the interconnect contacts can comprise projections formed on a silicon substrate and covered with a conductive layer.
As with semiconductor components, the external contacts for an interconnect are often formed on both sides of the interconnect. For example, a probe card can include contacts on its face for electrically engaging the component, and contacts on its back side for electrically engaging spring loaded pins (e.g., xe2x80x9cPOGO PINSxe2x80x9d) in electrical communication with test circuitry. U.S. Pat. No. 6,060,891 to Hembree et al. discloses this type of interconnect.
The present invention is directed to a method for fabricating semiconductor components and interconnects with contacts on opposing sides.
In accordance with the present invention, a method for fabricating semiconductor components and interconnects is provided. Also provided are improved components and interconnects fabricated using the method, and improved electronic assemblies and test systems incorporating the components and the interconnects.
Initially a substrate having a face side, an opposing back side and a plurality of substrate contacts on the face side. For fabricating semiconductor components, such as packages, the substrate can comprise a semiconductor die containing integrated circuits. The substrate contacts can comprise bond pads in electrical communication with the integrated circuits. For fabricating interconnects the substrate can comprise a semiconductor, a ceramic or a plastic. In addition, the substrate contacts can be dummies or omitted entirely.
The method also includes the step of forming vias through the substrate using a laser beam directed through the substrate contacts. The method also includes the steps of forming conductive members in the vias, and then forming external contacts on the face side and the back side of the substrate in electrical communication with the conductive members. The external contacts can also include a non-oxidizing layer which facilitates making permanent or temporary electrical connections with the external contacts. The external contacts on the face side and the back side can have matching patterns that allows identical components to be stacked to one another. Alternately the external contacts on the face side and the back side can be offset or redistributed with respect to one another.
A semiconductor component, such as a die, a package or a wafer, fabricated using the method, includes the substrate and the external contacts on the face side and the back side. The external contacts on the face side can be bonded to external contacts on the back side of an identical component to make a stacked assembly. An interconnect fabricated using the method includes the external contacts on the face side which can be configured to electrically engage a semiconductor component. The interconnect also includes external contacts on the back side which can be configured to electrically engage electrical connectors associated with test circuitry.
In an alternate embodiment of the method, the vias are initially formed as counter bores, and the conductive members are formed in the vias. The substrate is then thinned from the back side using a thinning process, such as chemical mechanical planarization (CMP) or etching, to expose the conductive members.
An electronic assembly includes multiple stacked components fabricated using the method. Another electronic assembly includes an interconnect fabricated using the method having semiconductor components attached to opposing sides. A test system for testing singulated components, such as dice and packages, includes a die level interconnect mounted to a test carrier configured to temporarily package the components. A test system for testing wafers, or other substrates containing multiple components, includes a wafer level interconnect mounted to a test apparatus such as a wafer prober.